Project 1: In our continued effort to understand the structure-function relationship of ras p21, we have made inframe deletions of 4-5 amino acids in the region of p21 protein as the epitope for anti-ras p21 monoclonal antibody, Y13-259. This antibody can revert the transforming effect of p21 and can also block the initiation of DNA synthesis. However, Y13-259 does not directly interfere with known biochemical properties of p21. These studies suggest that this antibody may affect some as yet undetected function of p21. To gain insights into the function of Y13-259 binding region of p21, these mutants are currently being analyzed for their biochemical and biological properties. Project 2: A novel oncogene, db1, isolated from a human diffuse B-cell lymphoma, has been previously shown to confer the transformed phenotype on NIH/3T3 cells. Our present studies were undertaken in an effort to identify the db1 oncogene product and to characterize some of its structural and functional properties. A 66,000 dalton protein (p66) has been identified in cells that have acquired db1 oncogene, while it is not present in cells transformed by other oncogenes or in untransformed NIH/3T3 cells. Furthermore, it is established that p66 is encoded by db1 oncogene. p66 is a phosphoprotein with serine a major site of phosphorylation and it is a cytoplasmic protein as judged by its subcellular distribution.